Migratory Birds of the Great Lakes University of Wisconsin Sea Grant Institute
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Expanding Cattails and Shrinking Sedge Meadows: Reversible?

Since the 1800s, half of Wisconsin’s primeval wetlands have been drained and filled in for agriculture, roads, houses and industry. Now the remaining wetlands have another threat.

Cattails blowing in the wind may be a familiar sight, but a closer look reveals they’re not all alike. The native species typically grow straight, sparse leaves that leave room for other types of plants to thrive. But the hybrid Typha x glauca, a cross between native and invasive cattails, is less hospitable.

“The hybrid cattails form very dense stands that use all the light above ground, and below ground the rhizomes fill up all the space. Hardly anything can coexist with it,” said Joy Zedler, who was awarded UW Sea Grant funding to study the problem. At risk are sedge meadows, one of the region’s most diverse types of wetland. The roots of native sedges, which are grass-like plants, form mounds that create nooks and crannies for other types of plants to live. They also provide excellent cover for birds and small animals.

The fluctuating water levels of the Great Lakes historically have sustained sedge meadows and kept cattails in check. Native cattails hug the waterline, while sedges grow just inland. Both plants prefer wet soil, and together they move upslope when water is high and recede when water levels drop. But it’s a different story with hybrid cattails, according to Christin Frieswyk, who received her doctorate working with Zedler.       next >>